1. Field of the Invention
The present invention generally relates to the field of cone-beam tomography systems, and more particularly to systems and methods for positioning patients in such systems.
2. Related Art
Cone beam computed tomography (CT) systems are widely employed and have many applications. In particular, they are becoming increasingly useful and prevalent within the dental industry. Such systems can be useful in the dental industry for a number of diagnostic and treatment procedures, including implants, temporomandibular joint (TMJ), orthodontics, impaction, orthognathic surgery, airway/sleep apnea studies, etc.
In x-ray imaging, an x-ray image of an object is created when x-rays are transmitted from a source through the object and collected on an image sensor or detector. The amount of x-ray radiation that reaches the sensor is related to the amount of attenuation that the x-ray encounters in the corresponding path through the object.
Broadly, computed tomography is a technique of reconstructing a three-dimensional image from a sequence of two-dimensional projection images. CT systems capture two-dimensional images and employ reconstruction algorithms to create three-dimensional images. Multiple projection images are used at different source-detector radiation angles relative to the object to obtain the required information to isolate a single plane in the object or create a complete three-dimensional reconstruction.
Cone-beam tomography directly captures three-dimensional information in a single scan. In cone-beam tomography, an x-ray source generates a cone-shaped illumination that is captured by a two-dimensional area detector. The source-detector assembly is scanned around the patient, resulting in the capture of a sequence of two-dimensional projection images. A direct three-dimensional reconstruction is then performed.
In a cone-beam tomography examination, it is useful for the patient to remain stationary in an assumed volume of space while the x-ray source and the source-detector assembly are scanned around the patient to capture the sequence of two-dimensional images in that assumed volume of space. However, it has been discovered that positioning the patient properly within that image volume, such as an orthodontic patient, presents a great clinical challenge and can affect image quality.